How to avoid overwrite strings while reducing an array?

I have an array grouped by different categories and each category have nested more objects with different values (numeric and strings) which i have to reduce (except the strings). Reduce is working fine with numeric values making a sum of them but its overwriting the string values keeping just the last one.

I'm trying to reduce an object/dictionnary by category and fill a table with the sum of the clicks of each category but don't sum them if the subcategories and names are different.